@Ashley ********
I'll make it easy and say they have two offices - Muang Thong Thani and Changwattana.
Changwattana: Nearest BTS station is Wat Phra Sri Mahathat
From there take taxi or motorcycle which will cost 70B or 100B.
For Muang Thong Thani, I believe you're best getting a taxi from Wat Phra Sri Mahathat BTS station.